Cannot resolve MX

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bajlek
Normal user
Normal user
Posts: 71
Joined: 2017-05-02 20:54

Cannot resolve MX

Post by bajlek » 2021-03-18 21:28

Hi, I have very strange situation on my hMailServer. I noticed that some email cannot be delivered because

Code: Select all

The following recipient(s) could not be reached:
objednavky@pentaservis.cz
Error Type: SMTP
Error Description: No mail servers appear to exists for the recipient's address.
Additional information: Please check that you have not misspelled the recipient's email address.
But sending email from different SMTP goes well without any problem. So I tried MX query from hMailserver console and got 0 results, but nslookup from windows system where hmailserver runs got 1 result and good result. I try change DNS servers without any change. There is only one solutions - edit hosts file (then I got MX query result from hMail). I restart domain controller where is basic dns cache, router, flushdns but nothing helps me.

This problem is only with few domains.

Can someone help me or pointed me to right direction?
Attachments
nslookup_pentaservis.jpg

User avatar
jimimaseye
Moderator
Moderator
Posts: 9220
Joined: 2011-09-08 17:48

Re: Cannot resolve MX

Post by jimimaseye » 2021-03-18 21:39

1, run this and post the results: viewtopic.php?f=20&t=30914

2, enable debug and smtp logging, try again, then post the results here.

[Entered by mobile. Excuse my spelling.]
5.7 on test.
SpamassassinForWindows 3.4.0 spamd service
AV: Clamwin + Clamd service + sanesecurity defs : https://www.hmailserver.com/forum/viewtopic.php?f=21&t=26829

bajlek
Normal user
Normal user
Posts: 71
Joined: 2017-05-02 20:54

Re: Cannot resolve MX

Post by bajlek » 2021-03-18 21:52

Code: Select all

2021-03-18   Hmailserver: 5.7.0-B2495

DOMAINS

   "Domain1.com" - crxxxxxxxxxxx.cz               Enabled: True

SIGNATURE         LIMITS                       DKIM               ADVANCED
  Enabled: False   Max size:                0   Enabled: True    
                   Max message size:        0   Header:   Relaxed  Plus addressing: False
                   Max size of accounts:    0   Body:     Relaxed
                                                Algorithm: SHA256  Greylisting:     False
                                                Private key: c:\program files\hmailserver\cert\dkim.Domain1.com.pem
                                                Selector:    mail
-----------------------------------------------------------------------------------------------

IP RANGES

IP: 192.168.2.138 - 192.168.2.151     Priority: 90     Name: tiskarny

  Allow connections                         Other
     SMTP:   True                              Antispam :  False
     POP3:  False                              Antivirus:  False
     IMAP:  False                              SSL/TLS:    False

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       - False
     Local To External    - False           
     External To Local    - False    
     External To External - False           


IP: 192.168.2.18 - 192.168.2.18     Priority: 85     Name: ERA

  Allow connections                         Other
     SMTP:   True                              Antispam :  False
     POP3:  False                              Antivirus:  False
     IMAP:  False                              SSL/TLS:    False

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       - False
     Local To External    - False           
     External To Local    - False    
     External To External - False           


IP: 192.168.2.253 - 192.168.2.254     Priority: 80     Name: iLO

  Allow connections                         Other
     SMTP:   True                              Antispam :  False
     POP3:  False                              Antivirus:  False
     IMAP:  False                              SSL/TLS:    False

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       - False
     Local To External    - False           
     External To Local    - False    
     External To External - False           


IP: 127.0.0.1 - 127.0.0.1     Priority: 50     Name: localhost

  Allow connections                         Other
     SMTP:   True                              Antispam :   True
     POP3:  False                              Antivirus:   True
     IMAP:   True                              SSL/TLS:     True

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       -  True
     Local To External    -  True              Local To External    -  True
     External To Local    -  True              External To Local    - False
     External To External - False           


IP: 192.168.2.10 - 192.168.2.10     Priority: 40     Name: server

  Allow connections                         Other
     SMTP:   True                              Antispam :  False
     POP3:  False                              Antivirus:  False
     IMAP:  False                              SSL/TLS:    False

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       - False
     Local To External    - False           
     External To Local    - False    
     External To External - False           


IP: 192.168.2.1 - 192.168.2.255     Priority: 30     Name: mistni sit

  Allow connections                         Other
     SMTP:   True                              Antispam :   True
     POP3:  False                              Antivirus:   True
     IMAP:   True                              SSL/TLS:     True

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       -  True
     Local To External    -  True              Local To External    -  True
     External To Local    -  True              External To Local    - False
     External To External - False           


IP: 0.0.0.0 - 255.255.255.255     Priority: 5     Name: internet

  Allow connections                         Other
     SMTP:   True                              Antispam :   True
     POP3:  False                              Antivirus:   True
     IMAP:   True                              SSL/TLS:     True

  Allow Deliveries from                     Require Authentication from
     Local To Local       -  True              Local To Local       -  True
     Local To External    -  True              Local To External    -  True
     External To Local    -  True              External To Local    - False
     External To External - False           


   !!  Warning:  DEFAULT DOMAIN is SET  !! - "Domain1.com"
------------------------------------------------------
AUTOBANNED Local Addresses:
    No entries

-----------------------------------------------------------------------------------------------

AUTOBAN
  Autoban Enabled: True       Max invalid logon attempts:     30
                              Minutes Before Reset:           15  (0,25 hours, 0,01 days)
                              Minutes to Autoban:             30  (0,50 hours, 0,02 days)

No problems were found in the IP range configuration.
-----------------------------------------------------------------------------------------------

INCOMING RELAYS
   No entries
-----------------------------------------------------------------------------------------------

MIRRORING         Disabled
-----------------------------------------------------------------------------------------------

PROTOCOLS

SMTP
GENERAL             DELIVERY                  RFC COMPLIANCE            ADVANCED
No. Connections:  0  No Retries:  4 Mins: 30   Plain Text:        False  Bind: 
                     Host: EXTERNAL.TLD        Empty sender:       True  Batch recipients:   100
Max Msg Size: 50480  Relay:-                   Incorrect endings:  True  Use STARTTLS:      True
                     (none entered)            Disc. on invalid:   True  Delivered-To hdr:  True
                                               Max number commands: 100  Loop limit:           5
                                                                         Recipient hosts:     15
  Routes:
     No routes defined.

POP3
 !! Service Not Enabled !!

IMAP
 GENERAL                   PUBLIC FOLDERS                    ADVANCED
  No. Connections:   0      Public folder name: _CREATIVECAP  IMAP sort:  True
                                                              IMAP Quota: False
                                                              IMAP Idle:  True
                                                              IMAP ACL:   True
                                                              Delim: "\"
-----------------------------------------------------------------------------------------------

ANTISPAM

GENERAL                              SPAM TESTS              Score   SPAMASSASSIN
  Spam Mark:                  6       Use SPF:            True - 2    Use Spamassassin:    True
  Add X-HmailServer-Spam:     True    Check HELO host:    True - 3    Hostname:       127.0.0.1
  Add X-HmailServer-Reason:   True    Check MX records:   True - 4    Port:                 783
  Add X-HmailServer-Subject:  True    Verify DKIM:        True - 2    Use SA score:        True
              Subject Text: "[SPAM]"
  Spam delete threshold: 20         Maximum message size: 2048

DNSBL ENTRIES:
                  zen.spamhaus.org      Score: 5     Result: 127.0.0.2-8|127.0.0.10-11
                    bl.spamcop.net      Score: 4     Result: 127.0.0.2
            b.barracudacentral.org      Score: 4     Result: 127.0.0.*
                   dnsbl.sorbs.net      Score: 2     Result: 127.0.0.*

SURBL ENTRIES:
                   multi.surbl.org      Score: 4

GREYLISTING:
  Greylisting:  False

WHITELISTING
              0.0.0.0            to    255.255.255.255              *[@t]vintagecork[dot]at
              0.0.0.0            to    255.255.255.255              *[@t]ucetni-portal[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]frucona[dot]sk
              0.0.0.0            to    255.255.255.255              *[@t]wineprotec[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]gastons[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]pernod-ricard[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]kapa-toner[dot]cz
              0.0.0.0            to    255.255.255.255              trnkaj[@t]centrum[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]j-plastik[dot]sk
              0.0.0.0            to    255.255.255.255              *[@t]aludium[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]portal[dot]mpsv[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]o2[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]mpsv[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]aludium[dot]net
              0.0.0.0            to    255.255.255.255              *[@t]aludium[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]chateaukrakovany[dot]sk
              0.0.0.0            to    255.255.255.255              *[@t]all4[dot]cz
              0.0.0.0            to    255.255.255.255              *[dot]sunlight[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]naturenotea[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]vinoblatel[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]vinarskyraj[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]mtcomax[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]3dwiser[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]gualaclosures[dot]com
              0.0.0.0            to    255.255.255.255              *[@t]vsvaltice[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]vinarstviukaplicky[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]nej[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]topvet[dot]cz
              0.0.0.0            to    255.255.255.255              *[@t]procork[dot]eu
-----------------------------------------------------------------------------------------------

ANTIVIRUS

GENERAL:
  When found - Delete email. Notify Sender: True,  Notify Receiver: True

  Max Message Size: 4092
     CLAM AV:   False
     CLAMWIN:   False
     CUSTOMAV:  True       Executable: "C:\Program Files\ESET\ESET Security\ecls.exe" /log-file="C:\Program Files\hMailServer\Logs\eset.log" /mailbox /unsafe /unwanted /preserve-time /clean-mode=delete "%FILE%"
                           ReturnValue: 1


  Block Attachments: True
               *._ba             
               *._ex             
               *._md             
               *._om             
               *.ade             
               *.adp             
               *.ba_             
               *.bat             Batch processing file
               *.cm_             
               *.cmd             Command file for Windows NT
               *.co_             
               *.com             Command
               *.cpl             Windows Control Panel extension
               *.csh             CSH script
               *.ex_             
               *.exe             Executable file
               *.hlp             
               *.hta             
               *.hta             
               *.chm             
               *.chm             
               *.inf             Setup file
               *.ins             
               *.isp             
               *.jar             
               *.js              
               *.jse             
               *.lib             
               *.lnk             Windows link file
               *.mde             
               *.ms_             
               *.msc             
               *.msh             
               *.msi             Windows Installer file
               *.msp             Windows Installer patch
               *.mst             
               *.pif             Program Information file
               *.reg             Registration key
               *.scf             Windows Explorer command
               *.scr             Windows Screen saver
               *.sct             
               *.shb             
               *.sys             
               *.vb              
               *.vbe             
               *.vbs             
               *.vxd             
               *.wsc             
               *.wsf             
               *.wsh             
-----------------------------------------------------------------------------------------------

SSL CERTIFICATES
   mail.Domain1.com
       Certificate: C:\Program Files\hMailServer\cert\ssl\fullchain.pem
       Private key: C:\Program Files\hMailServer\cert\ssl\privkey.pem
-----------------------------------------------------------------------------------------------

SSL/TLS
             TLS 1.0 :  False
             TLS 1.1 :  False
             TLS 1.2 :   True
             TLS 1.3 :   True                Verify Remote SSL/TLS Certs:   True
SslCipherList  :

ECDHE-RSA-AES128-GCM-SHA256     - ECDHE-ECDSA-AES128-GCM-SHA256   - ECDHE-RSA-AES256-GCM-SHA384     
ECDHE-ECDSA-AES256-GCM-SHA384   - DHE-RSA-AES128-GCM-SHA256       - DHE-DSS-AES128-GCM-SHA256       
kEDH+AESGCM                     - ECDHE-RSA-AES128-SHA256         - ECDHE-ECDSA-AES128-SHA256       
ECDHE-RSA-AES128-SHA            - ECDHE-ECDSA-AES128-SHA          - ECDHE-RSA-AES256-SHA384         
ECDHE-ECDSA-AES256-SHA384       - ECDHE-RSA-AES256-SHA            - ECDHE-ECDSA-AES256-SHA          
DHE-RSA-AES128-SHA256           - DHE-RSA-AES128-SHA              - DHE-DSS-AES128-SHA256           
DHE-RSA-AES256-SHA256           - DHE-DSS-AES256-SHA              - DHE-RSA-AES256-SHA              
AES128-GCM-SHA256               - AES256-GCM-SHA384               - ECDHE-RSA-RC4-SHA               
ECDHE-ECDSA-RC4-SHA             - AES128                          - AES256                          
RC4-SHA                         - HIGH                            - !aNULL                          
!eNULL                          - !EXPORT                         - !DES                            
!3DES                           - !MD5                            - !PSK;                           
-----------------------------------------------------------------------------------------------

TCPIP PORTS                                         Connection Sec
               0.0.0.0         / 25    / SMTP   -   StartTLS Optional   Cert: mail.Domain1.com
               0.0.0.0         / 143   / IMAP   -   StartTLS Optional   Cert: mail.Domain1.com
               0.0.0.0         / 465   / SMTP   -   SSL/TLS             Cert: mail.Domain1.com
               0.0.0.0         / 587   / SMTP   -   StartTLS Required   Cert: mail.Domain1.com
               0.0.0.0         / 993   / IMAP   -   SSL/TLS             Cert: mail.Domain1.com
-----------------------------------------------------------------------------------------------

LOGGING      Logging Enabled: True

  Paths:-
    Current:  C:\Program Files\hMailServer\Logs\hmailserver_2021-03-18.log
    Error:    C:\Program Files\hMailServer\Logs\ERROR_hmailserver_2021-03-18.log
    Event:    C:\Program Files\hMailServer\Logs\hmailserver_events.log - Last Event: 2021/03/18
    Awstats:  C:\Program Files\hMailServer\Logs\hmailserver_awstats.log
                        APPLICATION -    True
                        SMTP        -    True
                        POP3        -    True
                        IMAP        -      .
                        TCPIP       -    True
                        DEBUG       -      .
                        AWSTATS     -    True
-----------------------------------------------------------------------------------------------

SYSTEM TESTS

Database type: MSSQL

IPv6 support is available in operating system.

Backup directory D:\BACKUP is writable.

Relative message paths are stored in the database for all messages.

There are no error logs in the log directory.
-----------------------------------------------------------------------------------------------

HMAILSERVER.INI

[Directories]
Program folder:  C:\Program Files\hMailServer\
Database folder: 
Data folder:     D:\MBOX
Log folder:      C:\Program Files\hMailServer\Logs
Temp folder:     C:\Program Files\hMailServer\Temp
Event folder:    C:\Program Files\hMailServer\Events

[Database]
Type=              MSSQL
Username=          sa
PasswordEncryption=1
Port=              0
Server=            SRV-SQL\MAIL
Internal=          0
-----------------------------------------------------------------------------------------------

Generated by HMSSettingsDiagnostics v2.01, Hmailserver Forum.


DEBUG sending one email from webmail which run on the same subnet but different virtual machine

Code: Select all

"DEBUG"	5168	"2021-03-18 20:54:50.021"	"Pre-creating session 198"
"TCPIP"	5168	"2021-03-18 20:54:50.034"	"TCP - 192.168.2.38 connected to 192.168.2.40:587."
"DEBUG"	5168	"2021-03-18 20:54:50.039"	"TCP connection started for session 4"
"SMTPD"	5168	4	"2021-03-18 20:54:50.040"	"192.168.2.38"	"SENT: 220 mail.Domain1.cz"
"SMTPD"	5296	4	"2021-03-18 20:54:50.043"	"192.168.2.38"	"RECEIVED: EHLO posta.Domain1.cz"
"SMTPD"	5296	4	"2021-03-18 20:54:50.045"	"192.168.2.38"	"SENT: 250-mail.Domain1.cz[nl]250-SIZE 51691520[nl]250-STARTTLS[nl]250-AUTH LOGIN[nl]250 HELP"
"SMTPD"	5296	4	"2021-03-18 20:54:50.046"	"192.168.2.38"	"RECEIVED: STARTTLS"
"SMTPD"	5296	4	"2021-03-18 20:54:50.047"	"192.168.2.38"	"SENT: 220 Ready to start TLS"
"DEBUG"	5256	"2021-03-18 20:54:50.049"	"Performing SSL/TLS handshake for session 4. Verify certificate: False"
"TCPIP"	5168	"2021-03-18 20:54:50.084"	"TCPConnection - TLS/SSL handshake completed. Session Id: 4, Remote IP: 192.168.2.38, Version: TLSv1.3, Cipher: TLS_AES_256_GCM_SHA384, Bits: 256"
"SMTPD"	5296	4	"2021-03-18 20:54:50.085"	"192.168.2.38"	"RECEIVED: EHLO posta.Domain1.cz"
"SMTPD"	5296	4	"2021-03-18 20:54:50.086"	"192.168.2.38"	"SENT: 250-mail.Domain1.cz[nl]250-SIZE 51691520[nl]250-AUTH LOGIN[nl]250 HELP"
"SMTPD"	5296	4	"2021-03-18 20:54:50.088"	"192.168.2.38"	"RECEIVED: AUTH LOGIN"
"SMTPD"	5296	4	"2021-03-18 20:54:50.088"	"192.168.2.38"	"SENT: 334 VXNlcm5hbWU6"
"SMTPD"	5256	4	"2021-03-18 20:54:50.089"	"192.168.2.38"	"RECEIVED: YmlsZWtAY3JlYXRpdmUtY2Fwcy5jeg=="
"SMTPD"	5256	4	"2021-03-18 20:54:50.090"	"192.168.2.38"	"SENT: 334 UGFzc3dvcmQ6"
"SMTPD"	5256	4	"2021-03-18 20:54:50.091"	"192.168.2.38"	"RECEIVED: ***"
"SMTPD"	5256	4	"2021-03-18 20:54:50.105"	"192.168.2.38"	"SENT: 235 authenticated."
"SMTPD"	5256	4	"2021-03-18 20:54:50.108"	"192.168.2.38"	"RECEIVED: MAIL FROM:<bilek@Domain1.cz>"
"SMTPD"	5256	4	"2021-03-18 20:54:50.114"	"192.168.2.38"	"SENT: 250 OK"
"SMTPD"	5296	4	"2021-03-18 20:54:50.116"	"192.168.2.38"	"RECEIVED: RCPT TO:<objednavky@pentaservis.cz>"
"SMTPD"	5296	4	"2021-03-18 20:54:50.121"	"192.168.2.38"	"SENT: 250 OK"
"SMTPD"	5296	4	"2021-03-18 20:54:50.122"	"192.168.2.38"	"RECEIVED: DATA"
"SMTPD"	5296	4	"2021-03-18 20:54:50.123"	"192.168.2.38"	"SENT: 354 OK, send."
"DEBUG"	5256	"2021-03-18 20:54:50.172"	"Adding task AsynchronousTask to work queue Asynchronous task queue"
"DEBUG"	4324	"2021-03-18 20:54:50.174"	"Executing task AsynchronousTask in work queue Asynchronous task queue"
"DEBUG"	4324	"2021-03-18 20:54:50.177"	"Executing event OnAcceptMessage"
"DEBUG"	4324	"2021-03-18 20:54:50.180"	"Event completed"
"DEBUG"	4324	"2021-03-18 20:54:50.181"	"Saving message: {CD8133C4-9690-4BC1-933A-C84EF7D1C2D9}.eml"
"DEBUG"	4324	"2021-03-18 20:54:50.194"	"Requesting SMTPDeliveryManager to start message delivery"
"SMTPD"	4324	4	"2021-03-18 20:54:50.196"	"192.168.2.38"	"SENT: 250 Queued (0.047 seconds)"
"DEBUG"	4364	"2021-03-18 20:54:50.200"	"Adding task DeliveryTask to work queue SMTP delivery queue"
"DEBUG"	4760	"2021-03-18 20:54:50.202"	"Executing task DeliveryTask in work queue SMTP delivery queue"
"DEBUG"	4760	"2021-03-18 20:54:50.203"	"Delivering message..."
"APPLICATION"	4760	"2021-03-18 20:54:50.205"	"SMTPDeliverer - Message 297424: Delivering message from bilek@Domain1.cz to objednavky@pentaservis.cz. File: D:\MBOX\{CD8133C4-9690-4BC1-933A-C84EF7D1C2D9}.eml"
"DEBUG"	4760	"2021-03-18 20:54:50.206"	"Running custom virus scanner..."
"SMTPD"	5256	4	"2021-03-18 20:54:50.252"	"192.168.2.38"	"RECEIVED: QUIT"
"SMTPD"	5256	4	"2021-03-18 20:54:50.254"	"192.168.2.38"	"SENT: 221 goodbye"
"DEBUG"	5168	"2021-03-18 20:54:50.256"	"Ending session 4"
"DEBUG"	5296	"2021-03-18 20:54:50.258"	"Pre-creating session 199"
"TCPIP"	5296	"2021-03-18 20:54:50.259"	"TCP - 192.168.2.38 connected to 192.168.2.40:143."
"DEBUG"	5296	"2021-03-18 20:54:50.262"	"TCP connection started for session 197"
"DEBUG"	5168	"2021-03-18 20:54:50.265"	"Performing SSL/TLS handshake for session 197. Verify certificate: False"
"TCPIP"	5168	"2021-03-18 20:54:50.300"	"TCPConnection - TLS/SSL handshake completed. Session Id: 197, Remote IP: 192.168.2.38, Version: TLSv1.3, Cipher: TLS_AES_256_GCM_SHA384, Bits: 256"
"DEBUG"	5292	"2021-03-18 20:54:50.484"	"Saving message: {7AB77762-9A7E-4298-AABA-36965AB59D41}.eml"
"DEBUG"	5292	"2021-03-18 20:54:50.513"	"Ending session 197"
"DEBUG"	5296	"2021-03-18 20:54:51.070"	"Pre-creating session 200"
"TCPIP"	5296	"2021-03-18 20:54:51.075"	"TCP - 192.168.2.38 connected to 192.168.2.40:143."
"DEBUG"	5296	"2021-03-18 20:54:51.082"	"TCP connection started for session 199"
"DEBUG"	5296	"2021-03-18 20:54:51.088"	"Performing SSL/TLS handshake for session 199. Verify certificate: False"
"TCPIP"	5296	"2021-03-18 20:54:51.118"	"TCPConnection - TLS/SSL handshake completed. Session Id: 199, Remote IP: 192.168.2.38, Version: TLSv1.3, Cipher: TLS_AES_256_GCM_SHA384, Bits: 256"
"DEBUG"	5168	"2021-03-18 20:54:51.270"	"Ending session 199"
"DEBUG"	5296	"2021-03-18 20:54:51.480"	"Pre-creating session 201"
"TCPIP"	5296	"2021-03-18 20:54:51.484"	"TCP - 192.168.2.38 connected to 192.168.2.40:143."
"DEBUG"	5296	"2021-03-18 20:54:51.487"	"TCP connection started for session 200"
"DEBUG"	5296	"2021-03-18 20:54:51.489"	"Pre-creating session 202"
"TCPIP"	5296	"2021-03-18 20:54:51.490"	"TCP - 192.168.2.38 connected to 192.168.2.40:143."
"DEBUG"	5168	"2021-03-18 20:54:51.490"	"Performing SSL/TLS handshake for session 200. Verify certificate: False"
"DEBUG"	5296	"2021-03-18 20:54:51.493"	"TCP connection started for session 201"
"DEBUG"	5296	"2021-03-18 20:54:51.495"	"Performing SSL/TLS handshake for session 201. Verify certificate: False"
"TCPIP"	5256	"2021-03-18 20:54:51.526"	"TCPConnection - TLS/SSL handshake completed. Session Id: 200, Remote IP: 192.168.2.38, Version: TLSv1.3, Cipher: TLS_AES_256_GCM_SHA384, Bits: 256"
"TCPIP"	5296	"2021-03-18 20:54:51.528"	"TCPConnection - TLS/SSL handshake completed. Session Id: 201, Remote IP: 192.168.2.38, Version: TLSv1.3, Cipher: TLS_AES_256_GCM_SHA384, Bits: 256"
"DEBUG"	5292	"2021-03-18 20:54:51.641"	"Reading messages from database."
"DEBUG"	5264	"2021-03-18 20:54:51.712"	"Ending session 201"
"DEBUG"	5260	"2021-03-18 20:54:51.798"	"Ending session 200"
"DEBUG"	4760	"2021-03-18 20:54:53.121"	"Scanner: "C:\Program Files\ESET\ESET Security\ecls.exe" /log-file="C:\Program Files\hMailServer\Logs\eset.log" /mailbox /unsafe /unwanted /preserve-time /clean-mode=delete "D:\MBOX\{CD8133C4-9690-4BC1-933A-C84EF7D1C2D9}.eml". Return code: 0"
"DEBUG"	4760	"2021-03-18 20:54:53.123"	"Applying rules"
"DEBUG"	4760	"2021-03-18 20:54:53.124"	"Applying rule akcenta"
"DEBUG"	4760	"2021-03-18 20:54:53.124"	"Applying rule spam-penis"
"DEBUG"	4760	"2021-03-18 20:54:53.125"	"Applying rule spam-ostatni"
"DEBUG"	4760	"2021-03-18 20:54:53.126"	"Applying rule pravidla_od_uzivatelu"
"DEBUG"	4760	"2021-03-18 20:54:53.127"	"Performing local delivery"
"DEBUG"	4760	"2021-03-18 20:54:53.127"	"Local delivery completed"
"DEBUG"	4760	"2021-03-18 20:54:53.136"	"Signing message using DKIM..."
"TCPIP"	4760	"2021-03-18 20:54:53.196"	"DNS MX lookup: pentaservis.cz"
"TCPIP"	4760	"2021-03-18 20:54:53.260"	"DNS - MX Result: 0 IP addresses were found."
"APPLICATION"	4760	"2021-03-18 20:54:53.271"	"SMTPDeliverer - Message 297424: No mail servers could be found for the address objednavky@pentaservis.cz."
"DEBUG"	4760	"2021-03-18 20:54:53.272"	"Summarizing delivery result"
"DEBUG"	4760	"2021-03-18 20:54:53.274"	"Summarized delivery results"
"DEBUG"	4760	"2021-03-18 20:54:53.276"	"SD::RescheduleDelivery_"
"DEBUG"	4760	"2021-03-18 20:54:53.277"	"Retrieving retry options."
"DEBUG"	4760	"2021-03-18 20:54:53.279"	"Starting rescheduling."
"APPLICATION"	4760	"2021-03-18 20:54:53.281"	"SMTPDeliverer - Message 297424: Message could not be delivered. Scheduling it for later delivery in 30 minutes."
"DEBUG"	4760	"2021-03-18 20:54:53.283"	"PersistentMessage::SetNextTryTime()"
"DEBUG"	4760	"2021-03-18 20:54:53.288"	"PersistentMessage::~SetNextTryTime()"
"DEBUG"	4760	"2021-03-18 20:54:53.291"	"Message rescheduled for later delivery."
"APPLICATION"	4760	"2021-03-18 20:54:53.292"	"SMTPDeliverer - Message 297424: Message delivery thread completed."

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Re: Cannot resolve MX

Post by SorenR » 2021-03-18 22:37

bajlek wrote:
2021-03-18 21:28
Hi, I have very strange situation on my hMailServer. I noticed that some email cannot be delivered because

Code: Select all

The following recipient(s) could not be reached:
objednavky@pentaservis.cz
Error Type: SMTP
Error Description: No mail servers appear to exists for the recipient's address.
Additional information: Please check that you have not misspelled the recipient's email address.
But sending email from different SMTP goes well without any problem. So I tried MX query from hMailserver console and got 0 results, but nslookup from windows system where hmailserver runs got 1 result and good result. I try change DNS servers without any change. There is only one solutions - edit hosts file (then I got MX query result from hMail). I restart domain controller where is basic dns cache, router, flushdns but nothing helps me.

This problem is only with few domains.

Can someone help me or pointed me to right direction?
Quite simple. pentaservis.cz have a "Null MX" record in DNS telling hMailServer that they DO NOT accept mail.

When you do a lookup you'll find the DNS record "0 MX mail.pentaservis.cz"
The reason the "Null MX" record was inventet was if you do not have a MX record, the domain A-record is used as mailserver.

So Yes, hMailServer is correct in not being able to send mail to objednavky@pentaservis.cz.

"3. MX Resource Records Specifying Null MX"
https://tools.ietf.org/html/rfc7505#page-3

On the other hand it could also be an non-IT office worker with his head up his arse configuring the DNS and mailservice.... :roll:
Last edited by SorenR on 2021-03-18 22:41, edited 1 time in total.
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Re: Cannot resolve MX

Post by bajlek » 2021-03-18 22:40

LOL, OK, thank you I did not know that. So tell me why I can send them emails with different provider like Gmail?

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Re: Cannot resolve MX

Post by SorenR » 2021-03-18 22:43

bajlek wrote:
2021-03-18 22:40
LOL, OK, thank you I did not know that. So tell me why I can send them emails with different provider like Gmail?
For the reason I added to my original post while you posted your comment... :wink:
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Re: Cannot resolve MX

Post by bajlek » 2021-03-18 22:58

Thank you very much for your help!

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Re: Cannot resolve MX

Post by SorenR » 2021-03-18 23:17

bajlek wrote:
2021-03-18 22:58
Thank you very much for your help!
Actually... Looking at the source of hMailServer I do not see a deliberate omission of preference = 0. It seems the RFC is dated June 2015 and the hMailServer core code is much older than that so it may simply be ... ignored by design.

I'm not a skilled enough C++ programmer to determine that. Perhaps someone else can take a peep some day.

Perhaps you could add a change request on GitHub if you feel hMailServer need a configuration item to bypass the RFC?

I can confirm that my hMailServer 5.6.8 B2535.custom cannot resolve the MX record however my local DNS can.

Code: Select all

> set type=MX
> pentaservis.cz
Server:  192.168.0.6
Address:  192.168.0.6

Non-authoritative answer:
pentaservis.cz  MX preference = 0, mail exchanger = mail.pentaservis.cz
>
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Re: Cannot resolve MX

Post by bajlek » 2021-03-18 23:58

SorenR wrote:
2021-03-18 23:17
Perhaps you could add a change request on GitHub if you feel hMailServer need a configuration item to bypass the RFC?
I can confirm that my hMailServer 5.6.8 B2535.custom cannot resolve the MX record however my local DNS can.
I send information to administrator of pentaservis.cz and to their postmaster and webmaster to change DNS record to something else and If they really need 0 than to tell me why :-) RFS should not be bypassed right?

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Re: Cannot resolve MX

Post by mikedibella » 2021-03-19 00:55

The RFC says a "Null MX" is designated by
an RDATA section consisting of preference number 0 and a zero-length label, written in master files as ".", as the exchange domain, to denote that there exists no mail exchanger for a domain.
So you need both Preference=0 and Host="." to "turn off" the default hostname lookup. Just having Preference=0 does not constitute a "Null MX" designation.

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Re: Cannot resolve MX

Post by mikedibella » 2021-03-19 01:07

My guess is that either you are experiencing timeouts on some DNS queries. If you are using forwarders in your local DNS server configuration, increase the forward query time out. If you are using root hints, set the server timeout highter or consider configuring conditional forwarders for the problem domains and set to a global DNS provider (Google, Quad9, etc).

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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 01:08

Hmm... Yes Mike, you are correct!

How could I have missed that? well besides it is late here, my brain is hurting after spending the afternoon watching "The Snyder Cut" with the kids ... 4 hours 2 mins ... :|

So, we found ourselves a bug? :roll:

BTW, I found this..

DNSResolver.cpp line 359 refer to RFC 2812 (dated 2001) section 5

Code: Select all

5. Address Resolution and Mail Handling

   Once an SMTP client lexically identifies a domain to which mail will
   be delivered for processing (as described in sections 3.6 and 3.7), a
   DNS lookup MUST be performed to resolve the domain name [22].  The
   names are expected to be fully-qualified domain names (FQDNs):
   mechanisms for inferring FQDNs from partial names or local aliases
   are outside of this specification and, due to a history of problems,
   are generally discouraged.  The lookup first attempts to locate an MX
   record associated with the name.  If a CNAME record is found instead,
   the resulting name is processed as if it were the initial name.  If
   no MX records are found, but an A RR is found, the A RR is treated as
   if it was associated with an implicit MX RR, with a preference of 0,
   pointing to that host.  If one or more MX RRs are found for a given
   name, SMTP systems MUST NOT utilize any A RRs associated with that
   name unless they are located using the MX RRs; the "implicit MX" rule
   above applies only if there are no MX records present.  If MX records
   are present, but none of them are usable, this situation MUST be
   reported as an error.
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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 01:10

mikedibella wrote:
2021-03-19 01:07
My guess is that either you are experiencing timeouts on some DNS queries. If you are using forwarders in your local DNS server configuration, increase the forward query time out. If you are using root hints, set the server timeout highter or consider configuring conditional forwarders for the problem domains and set to a global DNS provider (Google, Quad9, etc).
I've been toying with hMailServer and my local DNS for the last hour or so... From the GUI I simply cannot make it identify a priority 0 MX record.
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Re: Cannot resolve MX

Post by mikedibella » 2021-03-19 01:19

but an A RR is found, the A RR is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host.
My read of this section is to say your code for DNS handling "fall back" if no MX records exists, should look up an A record for the domain and if one if found, set the hostname to the mail exchanger for the domain with Preference set to "0".

I think this is just saying that if the query returns more than one result, that they are all to be treated the same priority; that ordering of the result does not imply preference.

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Re: Cannot resolve MX

Post by mikedibella » 2021-03-19 01:22

SorenR wrote:
2021-03-19 01:10
From the GUI I simply cannot make it identify a priority 0 MX record.
I have Preference 0 records in some of my domains going back decades. Utilities | MX-query resolves these domains just fine.

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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 01:42

mikedibella wrote:
2021-03-19 01:22
SorenR wrote:
2021-03-19 01:10
From the GUI I simply cannot make it identify a priority 0 MX record.
I have Preference 0 records in some of my domains going back decades. Utilities | MX-query resolves these domains just fine.
That's where mine fail.

I think I am having some weird cache issue here. nslookup show exact records where hMailAdmin only show first lookup regardless of whatever changes I make in DNS after that.

My test server runs on WS2019, it's a relay so all cache in hMailServer is off. WS2019 also host the DNS.

I guess we are assuming GUI is using same code as server ?
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Re: Cannot resolve MX

Post by mikedibella » 2021-03-19 01:51

SorenR wrote:
2021-03-19 01:42
I think I am having some weird cache issue here.
Remember to clear the client cache (ipconfig /flushdns) as well as the server cache.

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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 02:13

mikedibella wrote:
2021-03-19 01:51
SorenR wrote:
2021-03-19 01:42
I think I am having some weird cache issue here.
Remember to clear the client cache (ipconfig /flushdns) as well as the server cache.
That is so wrong!

It's a server, not some john doe browsing 1000's of pages on porn sites all day!

OK, so my primary server now have "DNS Client" disabled but my secondary server is a bit tricky since it is hosting the DNS...

If first query result in empty response then this is cached for I don't know how long...

Now the GUI returns an ip address for objednavky@pentaservis.cz... It did not the first time I tried - and it remembered it!

/(&%%&¤¤ Windows !
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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 02:36

Enabled the "DNS Client" again and did this...

Looks like it works fine on Windows Server 2003 R2 and Windows Server 2019 Essential (also hosting DNS)

Code: Select all

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters]
"MaxCacheTtl"=dword:00000001
"MaxNegativeCacheTtl"=dword:00000000
Use at your own risk !
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Re: Cannot resolve MX

Post by mikedibella » 2021-03-19 02:36

SorenR wrote:
2021-03-19 02:13
That is so wrong!
Remember HMS resolver code is only going to be impacted by the DnsCache service if Win APIs are used for DNS resolution. If the code builds it's own message structures and just uses socket calls, those queries won't be cached by DnsCache.

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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 02:56

mikedibella wrote:
2021-03-19 02:36
SorenR wrote:
2021-03-19 02:13
That is so wrong!
Remember HMS resolver code is only going to be impacted by the DnsCache service if Win APIs are used for DNS resolution. If the code builds it's own message structures and just uses socket calls, those queries won't be cached by DnsCache.
Both RMSPF.cpp and DNSResolver.cpp link to winDNS.h from the Windows SDK.
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Re: Cannot resolve MX

Post by SorenR » 2021-03-19 15:32

Still trying to my head around what occured here.

I had the exact same symptoms as OP - hMailAdmin would not resolve the MX but NSLOOKUP could and it came out priority as 0, all other MX'es that I knew of would resolve on the spot.

It turns out hMailServer is using winDNS.h from the Windows SDK. Meaning it is using Windows "DNS Client" as cache.

DNS lookups have 3 states; Found, NotFound and SERVFAIL.

Found records are cached for as long as the record TTL - typical 3600 seconds = 1 hour.
NotFound records are cached for as long as the SOA record TTL - typical 86400 seconds = 24 hours.
SERVFAIL should NOT BE CACHED...

Clearly something went wrong. hMailAdmin could not resolve the MX and continued to do that for at least half an hour while NSLOOKUP gladly resolved the MX every time.

As I posted earlier I have modified my Windows registry to limit caching of "found" records to 1 second - and disabled caching of "NotFound" records.
My reason for doing this is this is a server, it is not doing thousands of DNS lookups per hour so I can decomission the cache to my local DNS server.

I will revisit this issue from time to time.
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Re: Cannot resolve MX

Post by jimimaseye » 2021-03-19 21:58

For the record....

I see almost every post that appears on the forum and the level of interest I take depends on the subject and detail of post (and length, jimbus). My lack of response by me doesn't mean that the posts have not been appreciated or unimportant. I am constantly amazed and proud by the level of detail our regulars contribute and this thread is the epitome of that.

Well done soren, mike and the rest of the helpers on the forum.
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SpamassassinForWindows 3.4.0 spamd service
AV: Clamwin + Clamd service + sanesecurity defs : https://www.hmailserver.com/forum/viewtopic.php?f=21&t=26829

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Re: Cannot resolve MX

Post by bajlek » 2021-03-29 21:47

Hi guys, so they changed DNS record and now it have 10 MX mail.pentaservis.cz but still does not work. I set up 1.1.1.1 and 8.8.8.8 to my Windows Server 2012 R2 server as forwarders. No change. Set up my provider DNS gues what ... no change. Set up DNS servers as static no change. So I dont know why hmailserver cannot resolve this MX recoed if windows 10 nslookup does. What am I doing wrong?

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Re: Cannot resolve MX

Post by mikedibella » 2021-03-29 23:01

From what I see you do not have your MX record configured correctly. This is the query result:

Code: Select all

> server 1.1.1.1
Default Server:  one.one.one.one
Address:  1.1.1.1

> set type=mx
> mail.pentaservis.cz
Server:  one.one.one.one
Address:  1.1.1.1

Non-authoritative answer:
mail.pentaservis.cz     canonical name = locator.cpsnet.cz

cpsnet.cz
        primary name server = eda.cps.cz
        responsible mail addr = admin.cpsnet.cz
        serial  = 2020060112
        refresh = 3600 (1 hour)
        retry   = 3600 (1 hour)
        expire  = 86400 (1 day)
        default TTL = 3600 (1 hour)
>

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Re: Cannot resolve MX

Post by bajlek » 2021-03-29 23:29

mikedibella wrote:
2021-03-29 23:01
From what I see you do not have your MX record configured correctly. This is the query result:

Code: Select all

> server 1.1.1.1
Default Server:  one.one.one.one
Address:  1.1.1.1

> set type=mx
> mail.pentaservis.cz
Server:  one.one.one.one
Address:  1.1.1.1

Non-authoritative answer:
mail.pentaservis.cz     canonical name = locator.cpsnet.cz

cpsnet.cz
        primary name server = eda.cps.cz
        responsible mail addr = admin.cpsnet.cz
        serial  = 2020060112
        refresh = 3600 (1 hour)
        retry   = 3600 (1 hour)
        expire  = 86400 (1 day)
        default TTL = 3600 (1 hour)
>
It is not my record and not my domain :-) What should I told them? :-)

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Re: Cannot resolve MX

Post by mikedibella » 2021-03-29 23:46

I queried the wrong record. Your MX record looks good:

Code: Select all

> server 1.1.1.1
Default Server:  one.one.one.one
Address:  1.1.1.1

> set type=mx
> pentaservis.cz
Server:  one.one.one.one
Address:  1.1.1.1

Non-authoritative answer:
pentaservis.cz  MX preference = 10, mail exchanger = mail.pentaservis.cz
>
Your A record is also present:

Code: Select all

> mail.pentaservis.cz
Server:  one.one.one.one
Address:  1.1.1.1

Non-authoritative answer:
Name:    locator.cpsnet.cz
Address:  193.104.7.35
Aliases:  mail.pentaservis.cz

>
There is a mail server at 193.104.7.35, but it is NOT hMailServer...see https://mxtoolbox.com/SuperTool.aspx?ac ... n=toolpage.

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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 00:05

Hmm ... mxtoolbox says MX for pentaservis.cz is 193.104.7.35 and it's preference 10.

https://mxtoolbox.com/SuperTool.aspx?ac ... n=toolpage

Also...
pentaservis.cz.jpg
On your hmailserver press the windows button and type services.msc - see if you can stop the DNS Client (dnscache) service and try to resolve it again from the GUI...
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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 07:33

Yes, this is very strange :-/

I disabled DNS cache thru registry

Code: Select all

Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Dnscache,
Locate the Start registry key and change its value from 2 (Automatic) to 4 (Disabled)
Reboot a and test again with the same result (no record from GUI)

hMailServer runs on Windows 10 Pro in Hyper-V. It is part of company domain. First DC1 (internal IP 192.168.2.10) is WS 2012 R2 Essentials with some special server roles and services, DC2 (192.168.2.17) is only AD replication of DC1. DHCP runs on MikroTik GW and put 192.168.2.10 ad 17 as primary and secondary DNS. On DC1 is forwarders ISP DNS servers (but I tried also different one).

Of course that I ipconfig /flushdns every time I try query domain "pentaservis.cz" on W10 (where hMailServer runs), DC1, DC2 and also in GW

Strange is that nslookup query is OK, but GUI of hMailServer cannot resolve it :( beside .... everything runs without any problems and hMailServer is very cool.
If I run hMailServer GUI query on different costumer (also different ISP) > no problem!! :-/

Code: Select all

hMailServer with error 5.7.0-B2495 x64 MSSQL DB 5700
hMailServer without error 5.6.8-B2494 MySL DB 5601

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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 08:24

According to this

https://docs.microsoft.com/en-us/window ... dns-client

"NSLOOKUP doesn't use the client's DNS cache, name resolution will use the client's configured DNS server."

And since NSLOOKUP is able to resolve the MX record, it tells me this most likely is a problem with the W10 instance.

If you flush dnscache on W10, then try to resolve via GUI and then do "ipconfig /displaydns" on W10 what do you see?
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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 08:44

ipconfig /flushdns
query with GUI pentaservis.cz = no result (blank)
ipconfig /displaydns

Code: Select all

Windows IP Configuration

    pentaservis.cz
    ----------------------------------------
    Record Name . . . . . : pentaservis.cz
    Record Type . . . . . : 15
    Time To Live  . . . . : 44557
    Data Length . . . . . : 16
    Section . . . . . . . : Answer
    MX Record . . . . . . : mail.pentaservis.cz
                            10
                            0


    mail.pentaservis.cz
    ----------------------------------------
    Record Name . . . . . : mail.pentaservis.cz
    Record Type . . . . . : 5
    Time To Live  . . . . : 3458
    Data Length . . . . . : 8
    Section . . . . . . . : Answer
    CNAME Record  . . . . : locator.cpsnet.cz


    Record Name . . . . . : locator.cpsnet.cz
    Record Type . . . . . : 1
    Time To Live  . . . . : 3458
    Data Length . . . . . : 4
    Section . . . . . . . : Answer
    A (Host) Record . . . : 193.104.7.35

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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 09:01

That's what I get too...

I was reading this https://exchangepedia.com/2006/12/shoul ... iases.html and that could be the problem... Domain -> MX (CNAME) -> A record. It should be Domain -> MX (A record).

Since 5.6.8 is able to resolve pentaservis.cz (did you try it on your W10?) and 5.7 is not able to resolve pentaservis.cz it _could_ be something in the 5.7 code. Is 5.7 simply not doing the second resolve for mail.pentaservis.cz?

I'll have a look but I can't fix it if that is the problem. 1: Something is rotten @ github - compiling fails due to missing BOOST library and 2: I don't have a fork of 5.7 since I don't use it myself :wink:
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 09:04

https://www.rfc-editor.org/rfc/rfc2181.txt
10.3. MX and NS records

The domain name used as the value of a NS resource record, or part of
the value of a MX resource record must not be an alias. Not only is
the specification clear on this point, but using an alias in either
of these positions neither works as well as might be hoped, nor well
fulfills the ambition that may have led to this approach. This
domain name must have as its value one or more address records.
Currently those will be A records, however in the future other record
types giving addressing information may be acceptable. It can also
have other RRs, but never a CNAME RR.
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 09:12

Could you make pentaservis.cz add a MX 20 pointing to locator.cpsnet.cz ???

DNS Resolver in 5.7 is totally rewritten compared to 5.6.8.
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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 09:22

SorenR wrote:
2021-03-30 09:01
That's what I get too...

I was reading this https://exchangepedia.com/2006/12/shoul ... iases.html and that could be the problem... Domain -> MX (CNAME) -> A record. It should be Domain -> MX (A record).

Since 5.6.8 is able to resolve pentaservis.cz (did you try it on your W10?) and 5.7 is not able to resolve pentaservis.cz it _could_ be something in the 5.7 code. Is 5.7 simply not doing the second resolve for mail.pentaservis.cz?

I'll have a look but I can't fix it if that is the problem. 1: Something is rotten @ github - compiling fails due to missing BOOST library and 2: I don't have a fork of 5.7 since I don't use it myself :wink:
Thank you for that information, I send email to pentaservis.cz to make it right. I use hMailServer 5.7 x64 because of higher TLS support I think, and also because I migrate data from old server to new one and with 5.6.8 migration stops :-/ and TLS 1.2 client GUI support
SorenR wrote:
2021-03-30 09:12
Could you make pentaservis.cz add a MX 20 pointing to locator.cpsnet.cz ???

DNS Resolver in 5.7 is totally rewritten compared to 5.6.8.
Already did, but I dont know their IT or support for webhosting and dns records, so I don't know how long will it take.

Should I upgrade to Build-2519 x64 ?

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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 09:30

bajlek wrote:
2021-03-30 09:22
SorenR wrote:
2021-03-30 09:01
That's what I get too...

I was reading this https://exchangepedia.com/2006/12/shoul ... iases.html and that could be the problem... Domain -> MX (CNAME) -> A record. It should be Domain -> MX (A record).

Since 5.6.8 is able to resolve pentaservis.cz (did you try it on your W10?) and 5.7 is not able to resolve pentaservis.cz it _could_ be something in the 5.7 code. Is 5.7 simply not doing the second resolve for mail.pentaservis.cz?

I'll have a look but I can't fix it if that is the problem. 1: Something is rotten @ github - compiling fails due to missing BOOST library and 2: I don't have a fork of 5.7 since I don't use it myself :wink:
Thank you for that information, I send email to pentaservis.cz to make it right. I use hMailServer 5.7 x64because of higher TLS support I think, and also because I migrate data from old server to new one and with 5.6.8 migration stops :-/

Should I upgrade to Build-2519 x64 ?
5.6.8 support TLS 1.3 ... 5.7 is an alpha release, it is bound to do weird things at some point. To have the same mods in 5.6.8 as you'll find in 5.7 you need to use the alternative 5.6.8 branch maintained by RvdH.

viewtopic.php?p=227993#p227993
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 09:34

I think 5.6.x is gentle (basically simply by the way the DNSlookup is written) and tries to resolve a MX -> CNAME record anyway as SorenR pointed out....5.7.x acts conform the RFC, MX cannot resolve to a CNAME
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 09:39

Thank you, I will make snapshot before I begin.
So there is installer https://build.hmailserver.com/viewLog.h ... =artifacts what is the right method of upgrade?

1.Reinstall by hMailServer-5.6.8-B2538.exe
2. extract hMailServer-5.6.8-B2538-Symbols.zip (PDB file)
3. overwrite files from https://d-fault.nl/files/hMailServer-Bu ... 2538.29.7z

Right?

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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 09:40

RvdH wrote:
2021-03-30 09:34
I think 5.6.x is gentle (basically simply by the way the DNSlookup is written) and tries to resolve a MX -> CNAME record anyway as SorenR pointed out....5.7.x acts conform the RFC, MX cannot resolve to a CNAME
Dont use query MX if record is cname. Is it better for example for antispam purposes?

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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 10:04

bajlek wrote:
2021-03-30 09:40
RvdH wrote:
2021-03-30 09:34
I think 5.6.x is gentle (basically simply by the way the DNSlookup is written) and tries to resolve a MX -> CNAME record anyway as SorenR pointed out....5.7.x acts conform the RFC, MX cannot resolve to a CNAME
Dont use query MX if record is cname. Is it better for example for antispam purposes?
RvdH wrote:
2021-03-30 09:04
https://www.rfc-editor.org/rfc/rfc2181.txt
10.3. MX and NS records

The domain name used as the value of a NS resource record, or part of
the value of a MX resource record must not be an alias. Not only is
the specification clear on this point, but using an alias in either
of these positions neither works as well as might be hoped, nor well
fulfills the ambition that may have led to this approach. This
domain name must have as its value one or more address records.
Currently those will be A records, however in the future other record
types giving addressing information may be acceptable. It can also
have other RRs, but never a CNAME RR.
It is NOT allowed to use a CNAME as MX record in the first place...the fact that 5.6.x resolves OK is basically wrong

With other words...fix your DNS record and make sure mail.pentaservis.cz resolves to IP (A-Record) or use locator.cpsnet.cz as MX record directly
Last edited by RvdH on 2021-03-30 10:31, edited 1 time in total.
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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 10:25

RvdH wrote:
2021-03-30 10:04
It is NOT allowed to use a CNAME as MX record in the first place...the fact that 5.6.x resolves OK is basically wrong

With other words...fix your DNS record and make sure mail.pentaservis.cz resolves to IP (A-Record)
It is not mine DNS records :-) it is company where my client cannot send email because of those errors ( 0 MX and CNAME as MX) but I already wrote them email to fix it :-)

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Re: Cannot resolve MX

Post by jimimaseye » 2021-03-30 13:15

FYI

I identified 2 or 3 years ago that Mx records entered as CNAMEs were causing lookup problems in 5.7 (where they did not have a problem in 5.6 production). This was reported on Github that martin has acknowledged with view to fix on 5.7. It is acknowledged that mx records SHOULDNT be entered as CNAMEs but they do exist and even some big players are incorrectly doing it. So although its easy to say "its their problem (for not following rules)" it doesnt help n your production environment and fixing our software to behave and adapt is preferable (just like it did on 5.6).
5.7 on test.
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Re: Cannot resolve MX

Post by bajlek » 2021-03-30 13:33

jimimaseye wrote:
2021-03-30 13:15
FYI

I identified 2 or 3 years ago that Mx records entered as CNAMEs were causing lookup problems in 5.7 (where they did not have a problem in 5.6 production). This was reported on Github that martin has acknowledged with view to fix on 5.7. It is acknowledged that mx records SHOULDNT be entered as CNAMEs but they do exist and even some big players are incorrectly doing it. So although its easy to say "its their problem (for not following rules)" it doesnt help n your production environment and fixing our software to behave and adapt is preferable (just like it did on 5.6).
Good point. So it is better to switch back to 5.6 version. Is it possible to do downgrade? I remeber that I needed 5.7 beccause of connection to MSSQL with secured TLS channel :-/

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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 14:08

jimimaseye wrote:
2021-03-30 13:15
FYI

I identified 2 or 3 years ago that Mx records entered as CNAMEs were causing lookup problems in 5.7 (where they did not have a problem in 5.6 production). This was reported on Github that martin has acknowledged with view to fix on 5.7. It is acknowledged that mx records SHOULDNT be entered as CNAMEs but they do exist and even some big players are incorrectly doing it. So although its easy to say "its their problem (for not following rules)" it doesnt help n your production environment and fixing our software to behave and adapt is preferable (just like it did on 5.6).
True and false....you have to play by the rules and therefore use the official allowed DNS format as defined in RFC
...saying even big players do it doesn't mean every mailserver does it and can still break stuff and therefore my advice stands... fix the MX record!
Last edited by RvdH on 2021-03-30 14:17, edited 1 time in total.
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 14:13

RvdH wrote:
2021-03-30 14:08
jimimaseye wrote:
2021-03-30 13:15
FYI

I identified 2 or 3 years ago that Mx records entered as CNAMEs were causing lookup problems in 5.7 (where they did not have a problem in 5.6 production). This was reported on Github that martin has acknowledged with view to fix on 5.7. It is acknowledged that mx records SHOULDNT be entered as CNAMEs but they do exist and even some big players are incorrectly doing it. So although its easy to say "its their problem (for not following rules)" it doesnt help n your production environment and fixing our software to behave and adapt is preferable (just like it did on 5.6).
True and false....always better to use the official allowed DNS format as defined in RFC
...saying even big players do it doesn't mean every mailserver does it and can still break stuff and therefore my advice stands... fix the MX record!
As it seems martin included a fix in 5.7 to resolve cnames for external mail server names, but that has nothing to do with MX records
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
DNS Lookup: d-fault.nl/DNSTools
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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 16:07

RvdH wrote:
2021-03-30 14:13
RvdH wrote:
2021-03-30 14:08
jimimaseye wrote:
2021-03-30 13:15
FYI

I identified 2 or 3 years ago that Mx records entered as CNAMEs were causing lookup problems in 5.7 (where they did not have a problem in 5.6 production). This was reported on Github that martin has acknowledged with view to fix on 5.7. It is acknowledged that mx records SHOULDNT be entered as CNAMEs but they do exist and even some big players are incorrectly doing it. So although its easy to say "its their problem (for not following rules)" it doesnt help n your production environment and fixing our software to behave and adapt is preferable (just like it did on 5.6).
True and false....always better to use the official allowed DNS format as defined in RFC
...saying even big players do it doesn't mean every mailserver does it and can still break stuff and therefore my advice stands... fix the MX record!
As it seems martin included a fix in 5.7 to resolve cnames for external mail server names, but that has nothing to do with MX records
It is not the first time someone broke something in a fix - just ask Microsoft.

Conversation between ignorant non-technical users - 99% of everyone on the Internet:

User A: Hey User B, I can't send mail to you, my server won't let me.
User B: Crappy software, Gmail can, get another software!
User A: Hey User B, I switched to GMail hosted domain - good advice. I'll remember to tell my friends hMailServer sucx!
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 16:30

Not the first 'issue' with the changed DNS lookup routine in 5.7.x builds, eg: https://github.com/hmailserver/hmailserver/pull/319

Well guess that's exactly why it is still ALPHA...i assume he currently is using an dravion 64-bit build that he has been posting publicly on the forums, to bad we can cleanup his mess (he left as it seems)
Last edited by RvdH on 2021-03-30 16:37, edited 4 times in total.
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
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Re: Cannot resolve MX

Post by jimimaseye » 2021-03-30 16:31

The real proof would be for someone with 5.6 to send an email to objednavky@pentaservis.cz to see if it goes.
5.7 on test.
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 16:34

jimimaseye wrote:
2021-03-30 16:31
The rela proof would be for someone with 5.6 to send an email to objednavky@pentaservis.cz to see if it goes.
Someone....or all of us? :mrgreen:
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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 16:38

MX records pointing to an IP address are illegal ... Sort of :wink:

hmailserver-master (5.7 ??) DNSResolver.cpp line 216 to 221 ...

Code: Select all

            {
               // Okay, this is an invalid MX record. The MX record should always contain 
               // a host name but in this case it appears an IP address. We'll be kind to
               // the domain owner and still deliver the email to him.
               a_records.push_back(hostName);
            }
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 16:41

SorenR wrote:
2021-03-30 16:38
MX records pointing to an IP address are illegal ... Sort of :wink:

hmailserver-master (5.7 ??) DNSResolver.cpp line 216 to 221 ...

Code: Select all

            {
               // Okay, this is an invalid MX record. The MX record should always contain 
               // a host name but in this case it appears an IP address. We'll be kind to
               // the domain owner and still deliver the email to him.
               a_records.push_back(hostName);
            }
Thats seems right, MX records should contain a FQDN....and this FQDN must resolve to a A-record (or AAAA record)
Looks like a simple workaround for someone who directly inserted a IP address as FQDN

i tend to agree with jimimaseye, although not following RFC, will be to simply resolve CNAMES for MX records as well
Best practice, fill/ format MX records according to the RFC's
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Re: Cannot resolve MX

Post by SorenR » 2021-03-30 16:53

RvdH wrote:
2021-03-30 16:30
Not the first 'issue' with the changed DNS lookup routine in 5.7.x builds, eg: https://github.com/hmailserver/hmailserver/pull/319

Well guess that's exactly why it is still ALPHA...i assume he currently is using an dravion 64-bit build that he has been posting publicly on the forums, to bad we can cleanup his mess (he left as it seems)
5.7.0-B2495 is Dravion ??

Wow, that's like talking about a Fiat 124 and it turns out to be a Lada 1200.. They look the same but one is Russian :mrgreen:
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 17:03

SorenR wrote:
2021-03-30 16:53
RvdH wrote:
2021-03-30 16:30
Not the first 'issue' with the changed DNS lookup routine in 5.7.x builds, eg: https://github.com/hmailserver/hmailserver/pull/319

Well guess that's exactly why it is still ALPHA...i assume he currently is using an dravion 64-bit build that he has been posting publicly on the forums, to bad we can cleanup his mess (he left as it seems)
5.7.0-B2495 is Dravion ??

Wow, that's like talking about a Fiat 124 and it turns out to be a Lada 1200.. They look the same but one is Russian :mrgreen:
Not sure, any other 5.7 builds havn't been posted directly on the forums i believe....

[EDIT]
Yup, viewtopic.php?t=34621 (Moderator(s), maybe simply delete them?)
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 17:26

viewtopic.php?p=220644#p220644
viewtopic.php?p=222860#p222860
Looks like this MX -> CNAME issue isn't that new...although i could not instantly remember it (getting old i think :mrgreen: )
CIDR to RegEx: d-fault.nl/CIDRtoRegEx
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Re: Cannot resolve MX

Post by johang » 2021-03-30 19:55

RvdH wrote:
2021-03-30 17:26
viewtopic.php?p=220644#p220644
viewtopic.php?p=222860#p222860
Looks like this MX -> CNAME issue isn't that new...although i could not instantly remember it (getting old i think :mrgreen: )
a little notable thing ... ALL of the examples are .cz domains ( is this just coincidence ? )

( when i tried to MX-query info@pentaservis.cz e in hmailserver GUI it would NOT resolve at my first click on the button.. but got Ipadress resolvment on second click, hmailserver 5.6.7 - B2425 ; and now it responds quickly all the time .. but not my first time .. )
lets cheat darwin out of his legacy, find a cure for cancer...

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Re: Cannot resolve MX

Post by RvdH » 2021-03-30 21:37

johang wrote:
2021-03-30 19:55
RvdH wrote:
2021-03-30 17:26
viewtopic.php?p=220644#p220644
viewtopic.php?p=222860#p222860
Looks like this MX -> CNAME issue isn't that new...although i could not instantly remember it (getting old i think :mrgreen: )
a little notable thing ... ALL of the examples are .cz domains ( is this just coincidence ? )
Maybe the Czech all need glasses to read the RFC's :lol: ... No, must be coincidence

johang wrote:
2021-03-30 19:55
( when i tried to MX-query info@pentaservis.cz e in hmailserver GUI it would NOT resolve at my first click on the button.. but got Ipadress resolvment on second click, hmailserver 5.6.7 - B2425 ; and now it responds quickly all the time .. but not my first time .. )
Probably just a timeout because the lookup is recursive in 5.6.x...
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Re: Cannot resolve MX

Post by mattg » 2021-03-31 06:32

RvdH wrote:
2021-03-30 17:03
Not sure, any other 5.7 builds havn't been posted directly on the forums i believe....

[EDIT]
Yup, viewtopic.php?t=34621 (Moderator(s), maybe simply delete them?)
gone now
Just 'cause I link to a page and say little else doesn't mean I am not being nice.
https://www.hmailserver.com/documentation

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Re: Cannot resolve MX

Post by bajlek » 2021-04-01 16:14

Hi guys, I just want to tell you that pentaservis.cz fix their DNS and now everything works like a charm. Should I fix my hMailServer version?

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Re: Cannot resolve MX

Post by SorenR » 2021-04-01 17:24

bajlek wrote:
2021-04-01 16:14
Hi guys, I just want to tell you that pentaservis.cz fix their DNS and now everything works like a charm. Should I fix my hMailServer version?
If you are using Dravions version then it is currently unsupported.

You have the option to switch to the official (ALPHA) version of 5.7 currently in development OR...

Revert back to 5.6.8 and choose the RvdH branch, it is synchronized with the official 5.6.8 and it holds all the new features of 5.7 plus more. Current version is from yesterday.
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Re: Cannot resolve MX

Post by bajlek » 2021-04-18 10:58

Hi guys, so I update hMailServer to 5.7.0-B2556 (x64) and I still have some issues with MX query from GUI.

When I try to resolve MX for mailbox blazek@bohemia-znak.cz I dont get any IP (just blank page). Nslookup is fine, checktls.com is OK (FAIL in cert). And yes, the problem is again in CNAME in MX record (mediasolution-mx.vshosting.cz).

I dont have energy to tell every company here in Czech Republic to follow the RFC :-( so....

Can you help me to downgrade to 5.6.8-B2494 because If I just re-install it I got error about DB version which is on my SQL Standard server. My DB version is 5700 but version of 5.6.8 uses 5601.

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